Browsing by Author "GU, C"

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A PRECISION EXPERIMENT ON ELECTRONS, PHOTONS AND MUONS AT LHC
(1993-02-01)
AZIZ, T
;
BOCK, R
;
BRAUNSCHWEIG, W
;
GEULIG, E
;
HILGERS, K
We describe the upgrade of the L3 detector for running at LHC. The principle goals are the precise measurement of electrons, photons and muons.
EFFECT OF POSITION-DEPENDENT TIME CONSTANT ON PHOTOREFRACTIVE 2-WAVE MIXING
(1992-09-01)
DAI, LK
;
GU, C
;
YEH, P
;
光電工程學系
;
Department of Photonics
The effect of a position-dependent time constant on nondegenerate photorefractive two-wave mixing is analyzed. For codirectional two-wave mixing the results indicate that the bandwidth of the two-wave-mixing gain decreases when the medium becomes lossy and that the photorefractive phase shift depends on the loss of the medium. In contradirectional two-wave mixing the total local intensity strongly depends on the coupling even if the medium is lossless. Thus the bandwidth is dependent on the energy coupling.
HOLOGRAM ENHANCEMENT IN PHOTOREFRACTIVE MEDIA
(1995-08-01)
YEH, PC
;
GU, C
;
CHENG, CJ
;
HSU, KY
;
光電工程學系
We consider the possibility of restoration and/or enhancement of decaying holograms in photorefractive media by using a simple optical readout in conjunction with a phase conjugator. The results indicate that extremely weak holograms can be enhanced provided that the two-beam coupling is sufficiently strong. Steady-state photorefractive holograms can be maintained continuously without decay by using a properly designed readout scheme. The result also provides an explanation for the formation of mutually pumped phase conjugation in terms of the amplification of initial noise gratings.
INSTABILITIES IN COUPLED PHOTOREFRACTIVE RING CAVITIES AND SELF-PUMPED PHASE CONJUGATORS
(1992-02-01)
DAI, LK
;
GOU, YS
;
GU, C
;
YEH, P
;
光電工程學系
In the preceding paper, we used the mean-field approximation to formulate the time evolution equations for two coupled unidirectional photorefractive ring resonators. Linear stability analysis based upon the steady-state solutions of the mean-field equations showed that the coupled system may become unstable in the unstable off- and steady-state operation regimes. In this paper, we investigate the temporal behavior and nonlinear dynamics of the coupled system. The results indicate that the coupled system exhibits self-pulsation and chaos in the unstable off-state and steady-state operation regimes. The instability is explained in terms of the competition between the nonlinear gain and loss. Numerical results of the transient equations are presented and discussed. The coupling between unidirectional ring resonators is extended to explain the instability in self-pumped phase conjugators.
INSTABILITIES IN COUPLED PHOTOREFRACTIVE RING CAVITIES AND SELF-PUMPED PHASE CONJUGATORS .1. MEAN-FIELD MODEL AND LINEAR-STABILITY ANALYSIS
(1992-01-01)
DAI, LK
;
GOU, YS
;
GU, C
;
YEH, P
;
光電工程學系
We investigate the temporal instabilities of mode intensities in two coupled unidirectional photorefractive ring resonators. The first resonator is driven by an external laser beam via photorefractive two-wave mixing. The internal oscillating beam is then employed to drive the second ring resonator. The second ring resonator provides a nonlinear loss mechanism for the coupled system. Complete spatial-temporal equations for describing the coupled system are derived and mean-field approximation is employed to simplify the transient analysis. The results of linear stability analysis indicate that the coupled system exhibits instability in the off-state and steady-state operation. The instability is explained in terms of competition between nonlinear gain and loss. The results are presented and discussed.
OPTICAL RESTORATION OF PHOTOREFRACTIVE HOLOGRAMS
(1995-11-01)
YEH, P
;
GU, C
;
CHENG, CJ
;
HSU, KY
;
光電工程學系
We consider the possibility of restoration and/or enhancement of decaying holograms in photorefractive media by using a simple optical readout in conjunction with a phase conjugator. The results indicate that extremely weak holograms can be enhanced provided that the two-beam coupling is sufficiently strong. Steady-state photorefractive holograms can be maintained continuously without decay by using a self-enhanced readout scheme. The results also provide an explanation for the formation of mutually pumped phase conjugation in terms of the amplification of an initial noise grating. The results are presented and discussed.
OPTICAL RESTORATION OF PHOTOREFRACTIVE HOLOGRAMS THROUGH SELF-ENHANCED DIFFRACTION
(1995-02-01)
CAMPBELL, S
;
YEH, PC
;
GU, C
;
LIN, SH
;
CHENG, CJ
For the first time to our knowledge, we demonstrate the use of self-enhanced diffraction to optically restore weak dynamic volume holograms. This restoration process is achieved through the use of a novel beam-toggling scheme that significantly enhances the steady-state diffraction efficiency of volume index gratings stored in photorefractive media. Experiments demonstrating and confirming theory are presented and discussed.
PHOTOREFRACTIVE MODE-COUPLING BETWEEN 2 UNIDIRECTIONAL RING OSCILLATORS
(1991-09-01)
DAI, LK
;
GOU, YS
;
YEH, P
;
GU, C
;
光電工程學系
We consider the coupling between two photorefractive unidirectional ring resonators. The first resonator is driven by an external laser beam via photorefractive two-wave mixing. The internal oscillating beam is then employed to drive the second ring resonator via the same mechanism. Closed form solutions for the oscillation intensities and frequencies are given, and their numerical results are presented and discussed. PACS: 42.65